----1.创建tb_student(name)索引  填充因子设为50
select * from tb_student
create nonclustered index huhu on tb_student(name) with (fillfactor=50)

--2.创建tb_record(borrow_time,return_time) 使用索引查询没还书的同学并且让没还书的同学将图书归还
create index huahua on tb_record(borrow_time,return_time)
select * from tb_record where return_time is null

----3.增加新列id() 创建聚集索引tb_book(id)

alter table tb_book add id int
go
drop index PK__tb_book__C16E36F9679CD14B on tb_book
create clustered index lala on tb_book(id)